The disclosure of Japanese Patent Application No. 2001-115489 filed on Apr. 13, 2001, including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The invention relates to a thermophotovoltaic power generating apparatus (TPV system) and a power generating method thereof for generating electric power based on the thermophotovoltaic energy conversion of infrared light (also termed infrared ray, or heat ray) radiated from a heat source via a photoelectric conversion element (photoelectric conversion cell).
2. Description of the Related Art
Thermophotovoltaic power generating apparatuses cause an emitter to radiate infrared light of a constant wavelength by heating the emitter, and cause the infrared light to strike a photoelectric conversion element so that the infrared light is converted into electric power. The thermophotovoltaic power generating apparatus, having no movable portion, are able to realize noiseless and nonvibrating systems.
As a next-generation energy source, thermophotovoltaic power generation is excellent in terms of cleanliness, quietness, etc. Combustion heat, solar heat, atomic disintegration heat, etc. are available to heat the emitter of a thermophotovoltaic power generating apparatus. Typically employed for heating the emitter is a combustion gas that is produced by combustion of a fuel gas, such as butane and the like.
For example, it is known to use a thermophotovoltaic power generating apparatus that includes an emitter formed from a porous solid, emitter heating means designed so that combustion gas passes inside the emitter, and a photoelectric conversion element that converts energy radiated from the emitter into electric energy.
The combustion of a gas fuel using a gas burner, which needs air, is dependent on the air temperature. However, the air temperature is not considered at all in the conventional thermophotovoltaic power generating apparatuses.
Furthermore, the conventional thermophotovoltaic power generating apparatuses do not effectively utilize exhaust gas that has heated the emitter. If the exhaust gas is subjected to heat recovery using an external thermal converter, the apparatus size increases, and the power generation efficiency reduces.
Still further in conventional flat-shaped thermophotovoltaic power generating apparatuses, the emitter is heated starting at a lower portion or an upper portion of the emitter, and only energy radiated from one surface of the emitter is received by a cell so as to generate electric power. Therefore, the power generating efficiency is low. Thus, the thermophotovoltaic power generating apparatuses are susceptible to improvement in terms of attainment of high photoelectric conversion efficiency.
Accordingly, it is one object of the invention to provide a thermophotovoltaic power generating apparatus whose electric power generating efficiency is improved by effectively using residual heat of a combustion gas that has already heated an emitter to heat air needed for combustion of a fuel, and by efficiently receiving on a photoelectric conversion element light radiated from the efficiently heated emitter.
In order to achieve the aforementioned and other objects, the invention provides a thermophotovoltaic power generating apparatus including an emitter that is heated by a combustion gas produced by a fuel and air supplied, and a photoelectric conversion element that receives light radiated from the emitter, and converts the light into electric power, wherein the air needed for combustion is pre-heated by residual heat of the combustion gas that has heated the emitter.
There is also provided a power generating method of a thermophotovoltaic power generating apparatus in which a emitter is heated by a combustion gas produced by a fuel and air, and light radiated from the emitter is converted into electric power by a photoelectric conversion element. In this method, the combustion gas that has heated the emitter is led to a vicinity of the air, and the air is pre-heated through a heat exchange between the combustion gas and the air.
In the thermophotovoltaic power generating apparatus and the power generating method thereof, the air needed for the combustion is pre-heated by residual heat of the combustion gas that has heated the emitter, and the pre-heated air is used to burn fuel. Therefore, the temperature of the combustion gas increases, and the temperature of the emitter correspondingly increases. As a result, the radiation intensity increases, and the electric power generated by the photoelectric conversion element increases. That is, the efficiency in conversion from thermal energy into electric energy improves.